The X-51 Hypersonic missile will be launched into action later this month. (Source: Weapons Blog)

Another view of the craft (Source: U.S. Air Force)

The U.S. Air Force is set to successfully launch a Boeing X-51 for 300 seconds of hypersonic flight

By
the end of this month, the U.S. Air Force will begin a series
of hypersonic tests
that will send a scramjet into the atmosphere for about five minutes,
at nearly five times the speed of sound. A scramjet is a supersonic
combustion ramjet, while a ramjet is a jet engine using the engine's
forward motion to compress air.

If all goes as planned,
this will be the first time that an aircraft will have flown at such
speeds for more than a few seconds of time.

In previous
attempts, the NASA X-43 was powered-up for just 10 seconds of
flight. The X-43 was tested four times in 2004 and was
hydrogen-powered.

This time around, the U.S. Air Force will be
testing the X-51 Waverunner, which runs on compressed air that
ignites fuel by combustion.
The X-51 is designed to be dropped from beneath a B-52 bomber.

A
rocket booster will ignite and accelerate the Waverunner. It
will then run its course -- from Mach 1 to Mach 6 -- under its own
power, at which time the nose of the X-51 is expected to reach
at least 1,480 degrees F.

The aircraft fuel will then be piped
through tubes around the engine surface and will help warm the fuel
to the temperature needed to ignite it as well as draw off heat to
keep the engine from melting.

According to Popular
Mechanics,
the X-51 Waverunner is a global strike missile that is part of the
Prompt Global Strike research project being developed by Boeing and
the U.S. Air Force Research Laboratory and Defense Advanced Research
Projects Agency.

The Waverunner is said to be a warhead
in the making, which will be filled with thousands of rods 12 times
as destructive as a .50-caliber bullet, targeted to shower a
designated area.

It is being developed for precision, speed,
and range and has been designed to strike any place on the planet in
an estimated 60 minutes.

The long-term goal is to design
airplanes and missiles that would reach Mach 25. The U.S. Air
Force plans to conduct up to four tests of the Waverunner this year.

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You can deliver nukes via subsonic cruise missile too (we did it with Tomahawks back in the 80s). Aside from cost the biggest potential savings with this is that it's relatively stealthy. Anyone with a few IR sats covering the globe can spot an ICBM launch; cruise missiles are much less energetic.

quote: I can't remember article, but it was said that these rods would hit the earth so hard they would go through 300 feet of solid steal.

If that is true, how much rock or reinforced concrete can it penetrate? A non explosive weapon as such could be used on underground facilities if they are locate near population centers without mass casualties from conventional or glow in the dark weapons.

The shrapnel damage to a tank from piercing it with a kinetic weapon is devastating.

The cost to take out Iran's underground nuke weapons facilities built near cities without mass public casualties for a billion is extraordinarily cheap.

Think of it this way. You've no doubt heard of the A-10 with the GAU-8 Avenger. It shoots 2100 rounds per minute [actually 4200 but that's another story] of 30mm. Wikipedia says "Muzzle velocity when firing Armor-Piercing Incendiary rounds is 3,250 feet per second."

Now imagine all 2100 rounds arriving at the same time. Consider Mach 5 to be about 3000 mph (which is about 4400 fps).

Or perhaps you've seen video of the AC-130H Spectre gunship firing....

All of that arriving at basically the same time represents a lot of energy. [No jokes about negative vibes, please 8]

Btw,http://www.globalsecurity.org/military/systems/air...says the cost is about $70 million for development costs, w/ an option for $60 mil to get to the flight stage [which is basically where we are now]. Fairly cheap. No idea what the per unit costs would be but probably not bad. $4-5 mil?

Having said that, I don't readily understand the strategic value, other than you have some bad-a$$ engine technology developed for future aircraft (what-have-you).

"I suppose if you think of going after O_ama Bin Laden you can't really use cruise missiles"

You can actually...but cruise missiles can take 2-3 hours to arrive, by which time your target may well have moved on. In fact, the primary impetus for this program (or so it's reported) was the failed Tomahawk attack on Bin Ladin, who left camp before the missile arrived.

You CAN do virtually anything. In fact, you CAN give me a bb gun and send me marching. The effectiveness may not be so hot, and it'll take a rather longer period of time than 2-3 hours 8) This was the context of my statement.

Clinton's Tomahawk's were launched on August 20, 1998. The HyTech and Fasthawk, which are feeder programs for the x-51, both pre-date that time. It is possible the given scenario is a primary impetus, but just that. Unless, you have a link that says otherwise?

" The HyTech and Fasthawk, which are feeder programs for the x-51, both pre-date that time."

Fasthawk was defunded in 1998, the same year it was reported that the small, low-funded HyTech wouldn't result in an actual hypersonic missile before 2015 at the earliest.

Then we missed Bin Laden in Afghanistan, and HyTech suddenly resurfaces as the much better funded and higher profile X-51 program, with first flight tests originally planned for 2009. Draw your own conclusions as to what sort of boost this incident gave the program.

Fueling for some ICBM missiles is at about one hour - this weapon's purpose is to be able to hit an ICBM site between the time it started fueling, and the time the ICBM is in flight. People are researching ways to bring down an ICBM in flight - but it's a small target (at most tens of square meters) moving at a very very high speed (and most of the time, it's very distant). Hitting them while staying on the launch pad is much easier (stationary missile and a lot of flammable substances) and safer (it's destroyed in the enemy's back yard).

I wonder if this thing would have enough energy to be a bunker-buster?

Lol! I keep trying to explain to people that "tactical" nuclear weapons became obsolete during the first Gulf War. The Air force took old 8" gun tubes, filled them with explosive, and put on an armor piercing cap and a GPU-14 precision guidance unit.

You may have heard about the case where about 500 family members of Iraq's ruling elite were killed in a nuclear bomb shelter. Dropping the bomb from a high enough altitude meant it arrived hypersonic and drilled through the top and bottom of the bomb shelter, and into a hardened command and control site under the shelter. Unfortunately for the families, the Iraqis had added a large fuel tank in the C&C facility, which resulted in a fuel-air explosion in the shelter above.

The Thor's Hammer trick with basically steerable crowbars arriving hypersonically can take out nuclear hardened missile silos. If liberals would stop hyperventilating about first strike capability and deploy this in orbit, ICBM would likewise become obsolete. A B-52 launched version is suboptimal, but much better than nothing. The important thing to remember is that these are much, much cheaper than nuclear weapons and/or any shielding that can defend your arsenal from kinetic strike.

They are also not real useful against soft targets like civilians and cities. You could drill a hole in the gold vault under the Federal Reserve Bank in New York. But if you attacked an average house, you would put a small hole in the roof, and in the basement floor, and a hundred feet or so underneath. ;-)

Err, like what? A basic chemical explosion by itself isn't very deadly...you need shrapnel to make it effective. These penetrating rods are just that: shrapnel pre-accelerated to deadly force by the missile itself. Replacing them with a high explosive charge of the same weight would result in a weapon less destructive (as well as less precise).

You could, of course, put a small nuclear warhead on the end...but that essentially defeats the entire purpose.

Err, the Russian thermobaric "Father of All Bombs" bomb had a little less than 50 tons TNT yield...it also weighed over 7 tons. You can't get a warhead that large on even a full-size ICBM..you think you can put it on a much smaller X-51?

Besides, you can't even deliver a fuel-air explosive at a velocity that high and have it successfully detonate....you'd have to somehow slow down the missile to make it even work.

"Seems like a helluva lot of trouble to get 1000lb bomb on target, no?"

It doesn't work like that. A bomb without shrapnel can only kill by overpressure or heat, neither of which are terribly effective (and both of which drop off very quickly...overpressure drops by the cube of distance).

So most bombs meant to kill (rather than simply penetrate) are designed to generate shrapnel....usually by bringing it with them. Often, this is just the bomb casing...designed to fragment into thousand of pieces from the force of the explosion.

The X-51 warhead, however, isn't a 1000 lb bomb that only contains 100 lbs of shrapnel. It's 100% shrapnel ... already accelerated and evenly dispersed over the target area. It's going to be at least an order of magnitude more destructive than a simple energy comparison would suggest.

I'm not sure you caught my point. Shrapnel is all well and good, but how much energy are you really bringing to the party?

I think the kinetic energy calc is spot on, so pardon me if I'm not overcome with warm fuzzy feelings 8) I was expecting something a bit more -- I don't know, perhaps on the order of Project Thor (like you and others have mentioned). Of course, with that, the velocity is more like 9000m/s. Something the size of a crowbar is going to do damage but it wouldn't exactly be a bunker buster. At that point, it's more of an assassination tool. If so, then we have more COST effective means of getting there [MQ-9's I've mentioned earlier].

I don't think the X-51 is going to penetrate 300 feet of steel. Likely quite a few feet, but the role of bunker buster is iffy. Methinks. So that limits the roles this tech can play. Hence less cost effective in my book. Damn interesting though.

Another thing, you wrote "evenly dispersed over the target area". I'm curious how these rods would be packed into the payload. I can see how something like 1/2" ball bearings could be packed and dispersed -- just use a small explosive charge, at a precise split instant before impact, to get a desired spread -- but dispersing rods? notta so fast there Kowalski. Sure you could disperse them but then keep them perpendicular to target? don't see it. And if you don't care about perpendicularity then why not use ball bearings, or Ninja stars (Hira-shuriken)?

It was, yes. However, as I said, energy alone is very poor at killing people. A man standing near an artillery simulator (essentially a quarter-stick of dynamite) will generally just be harmlessly blown through the air a few feet. On the contrary, just a couple pounds of pressure on a stiletto knife can kill. In a traditional bomb, most of the energy is wasted simply trying to accelerate shrapnel to lethal velocity.

"I don't think the X-51 is going to penetrate 300 feet of steel"

Nowhere near. I don't know where the previous poster got that figure.

"Sure you could disperse them but then keep them perpendicular to target? "

quote: To be honest, with such an expensive delivery system, I was expecting a much more destructive type of payload than this kinda crap.

I'm amazed that no one here has mentioned Footfall , written by Jerry Pournelle and Larry Niven. This type of weapon system (the orbitally-launched variant) is featured in the novel. When you do the math, you'll see that it's incredibly devastating. Something like this can make mincemeat out of a tank column with appropriate projectile dimensions and velocity.

Footfall was referencing Pournelle's "Thor" KE-based bombardment system. The projectiles in Thor were much higher energy (at NEO, the energy would be 30+ MJoules per kg) and, of course, much larger and heavier as well.

IIRC the original KE weapon of choice was Heinlein's idea, of using lunar boulders weighing a few tons apiece, strapping an iron girdle around them, then launching by an EM catapault at targets on Earth. Heinlein included steering rockets so as to provide precise targeting and also a last-minute abort procedure should the launchers change their minds. Effective KE was about 15 or 20 kilotons of TNT, since the Moon is near the top of the Earth's gravity potential energy. Sorta like an upscale railgun with really cheap ammunition :P.

0.50 BMG has about 20KJ of kinetic energy. 12x that would be 240 KJ kinetic energy. That is roughly equivalent to the 30 × 173 mm round on the GAU-8 Avenger (1/2)*(0.45kg) * (1080m/s)^2 = 243KJ.

Now at first even that might not seem to "bad ass" till you consider due to lead up/down in a burst by a good pilot only about 100-200 rounds from the A-10 will hit the target area.

Now the article says thousands of penetrators. Is that 2,000 or is it 9,000? Who knows. Lets guestimate and say it delivers 5,000 penetrators to the target area (each the equivelent of 30mm armor piercing auto cannon round).

Three major advantages:1) All rounds arrive simultaneously. Think giant no warning 30mm shotgun (with 5000 pellet armor piercing buckshot).2) It is stealthy and can hit a high value target anywhere in the world.3) It is the equivalent of 25 strafing passes from an A-10

So say you have a high value target spotted by CIA, drone, or some special forces unit. Pop off one of these and within an hour the target area without warning is showed with thousands of penetrators capable of defeating everything up to and including bunkers and main battle tanks.

This thing would be useful in a conventional war for a "shock and awe" or first strike type attack. Imagine what 5000 30mm rounds arriving simultaneously without warning would do to a tank formations, troops in assembly area, aircraft on runway, ammo dump, or command post.